Background Modelling in the ATLAS H to yy Differential Cross Section Analysis

Fiducial differential cross section measurements are an important part of the efforts to precisely measure the Higgs boson properties, providing model-independent measurements of kinematic and event observables. This poster presents the H to yy fiducial and differential cross section analysis using the full Run-2 data set taken between 2015 and 2018 at the ATLAS experiment. The analysis uses analytical functions to extract the signal yield in its signal + background fit to data, subsequently unfolding the fitted yields to the particle level. The background fit function is chosen from a list of considered functional forms by evaluating the potential measurement bias for each function using MC simulated samples. An emphasis is put on the explanation of the background modelling strategy and the estimation of the potential bias introduced to the measurement by the background model choice.